Improved method of operating cut-off valves



UNITED STATESA FFICE.

ATENT GREEN B. MCDONALD, OF LOUISVILLE7 KENTUCKY.

Specification forming part of Letters Patent No. 41,083, dated January 5, 1864; antedatcd January 2, i864.

To all whom it may concern:

Be it known that I, GREEN B. MoDoNALn, ot Louisville, in the county of Jefferson and State of Kentucky, have invented a new and useful Improvement in Variable Cut-Otfs for Steam-Engines; and I do hereby declare that the following is a full, clear, and exactdescription of the same, reference being had to the accompanying drawing, forming part ot' this specification, said drawing representing a vertical section showing the application of my invention to one ot the induction-valves of a steam-engine.

This invention relates to what are known as drop cut-offs, in which the closing of the induction-valve, or other valve employed for cutting oft' the steam, is edected by the weight of the valve itself or by a weight or spring connected therewith after such valve has been liberated from its opening mechanism.

It consists in certain novel means of regulating the closing of the said valve after its liberation, either by means of a manual adjustment or under the control of a governor.

To enable others skilled in the artto make and apply my invention, I will proceed to describe its construction and operation.

A is the indnction-valve,'and B its seat. O is the valve-stem, furnished with a lifter, D, which is raised to open the valve by a toe, E, operated by an eccentric, F, on the main shaft G, in a wellknown manner. I prefer that the toe shall be so constructed and arranged as to produce the whole opening movement of the valve during about onesixteeenth part ot' the revolution of the mai-n shaft. H is a piston secured to the valve stem and fitted to work easily within an upright cylinder, I, containing oil or other liquid. This piston has provided in it one or more openings, a a, each tted with a valve, b, which opens downward, and the cylinder is furnished with an outside pipe or passage, o, which forms a communication between its upper and lower parts, and the said pipe or passage is fitted with a butteriiy or other valve or cock, d, the spindle of which is furnished outside ofthe said pipe or passage with a lever, c, by which it is adjusted by handin a more or less open position, or connected with a governor in such a that its opening is increased by the rise of the governor at the commencement of any increase in the speed of the engine, and \i.e versa. The whole of the space within the cylinder I not occupied with the piston H should be lled with oil or other liquid.

As the valve A is lifted to admit steam to the engine and the piston H rises With it, the valves b b open to allow the free passage of liquid through the openings a a, from the upper to the lower side of the piston. As soon as the descent of the lifterE commences, and the valve A and piston H commence to descend by their own Weight, with or without the aid of l additional weights or springs, the valves b b close and prevent the return of the liquid through the piston, but the pressure of the piston upon the surface of the liquid below it forces the said liquid up throughthe passage c and the valve d, according as it is more or less open, checks in a greater or less degree the transit of the liquid through v the said passage from the upper to the lower side oi'l the piston, and so more or less checks the descent of the piston and the descent and closing of the valve A, causing the said valve to remain open, and admit steam to the engine during a greater or less portion of the stroke, thereby regulating the speed of the engine.

Vhen the invention -is applied directly to the inductiouvalve, a separate valve is used for each end ofthe cylinder, and a separate cylinder, I, and piston H are applied in connection with each valve; but in case of its application in connection with a single independent cut oft' valve, one cylinder, I, and piston H, will be sufcient.

ff are upright grooves formed in the lower part of the interior of the cylinder I, extending from the bottom thereof up to a height somewhat greater than the depth or thickness ofthe piston H. When the said piston has descended low enough to bring its upper side below the tops of the said grooves, the said grooves constitute passages for` the liquid in the lower part of the cylinder to pass up to the upperside thereof. The object of the said grooves is to enable the piston in all cases to descend quickly, and the valve A to close as quickly after the said piston has descended below the upper ends of the `said grooves, stanti-(illy as sind for the purpose herein specitliereby preventing wha-t is termed the wirefied. y

drawing ofthe steam. 2. The passages ff in the said cylinder I, What I claim as my invention, and desire arranged and operating in combination with to secure by Letters Patent, is the said piston H, substantiallyns and for the l. The piston H, fitted with a vulve or purpose herein described.

v.il\*es b b and the cylinder I furnished with l n side 7passage, c, and valve orooek d, and eon- G' B' MCDONALD taining oil or other liquid, applied in oombi- Vitnesses: A nation with each other and with the inclue- N. W. WALLER,

tion or other eut off valve A, to operate sub GEORGE AiNsLIE. 

